In recent years, attention has been given to multi-band antennas that can transmit and receive radio waves of a plurality of mutually different frequency bands. Specifically, different frequency bands, such as the 800 mega-hertz (MHz) band, 1.7 giga-hertz (GHz) band, and 2 GHz band, are currently used in radio communication systems in countries around the world, and therefore a multi-band antenna that can be used with the different frequency bands is under study.
Such a multi-band antenna typically includes antenna elements that resonate in response to respective radio waves in a plurality of frequency bands. When the multi-band antenna transmits or receives radio waves of any of the frequency bands, an antenna element corresponding to this frequency band resonates. Accordingly, in the case of increasing the number of frequency bands for which the antenna is suitable, the number of antenna elements tends to increase, which leads to an increase in the size of a multi-band antenna. To address this problem, various ideas regarding the shape of an antenna element have been proposed so as to reduce the size of a multi-band antenna.
Further, a structure in which a switch is coupled to an antenna element, and the switch is used to select whether power is fed to, for example, one antenna element or not, has been considered. This is intended to reduce the size of a multi-band antenna while allowing usage of the multi-band antenna with a plurality of frequency bands.